Updated

Aug. 1 marks the beginning of National Breast-feeding Month -- as well as the start of World Breast-feeding Week.

Of infants born in the U.S. in 2013, 81.1 percent were breast-fed -- with 51.8 percent breast-feeding at six months and 30.7 percent breast-feeding at 12 months, the Centers for Disease Control and Prevention (CDC) said.

The practice may offer babies and their moms a number of health benefits. Here’s what you should know.

The health benefits and effects for babies

Breast milk is “a great source of nutrition for the baby,” Dr. Deb Galuska, associate director of science with the CDC, told Fox News.

The milk offers health benefits and helps protect babies from diarrhea, ear infections and respiratory infections, she said, explaining that breast-fed babies are also at a lower risk for sudden infant death syndrome, diabetes and obesity.

There are also other positives. Breast-feeding is unique in that it “allows for the bond between the mother and the baby,” Dr. Martha Caprio, a neonatologist with NYU Langone Medical Center, told Fox News.

For breast-fed babies, weight gain may be lower compared to formula-fed babies, Caprio explained, citing the “Gerber-style” look. However, she said that it’s not considered a negative effect of breast-feeding.

“Benefits far outweigh” possible issues, she said.

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Benefits for moms

Women who breast-feed have a lower likelihood of breast cancer, ovarian cancer, type 2 diabetes and heart disease, Galuska said. Women can also maintain their weight and possibly lose weight, according to Caprio.

Are there times when women should not breast-feed?

Women who have HIV or take certain types of medications should avoid breast-feeding, Galuska said, explaining that they should talk to their doctor first. Though women who smoke may breast-feed, she said, “we would certainly encourage a woman who was smoking to quit smoking.”

How long should I breast-feed my baby?

Galuska said that the CDC follows the recommendation from the American Academy of Pediatrics, which involves exclusively breast-feeding - meaning no other liquids or foods - for the first six months. The AAP recommends adding food to the baby’s diet after that timeframe while continuing to breast-feed “until at least 12 months” or “as long as mutually desired by mother and baby.”

Continuing the practice past one year can have positive upsides for babies and moms, according to the Mayo Clinic.

“Extended breast-feeding — as well as breast-feeding for 12 months or more cumulatively in life — has been shown to reduce the risk of breast cancer, ovarian cancer, rheumatoid arthritis, high blood pressure, heart disease and diabetes” for a breast-feeding mom, the clinic says.

But long-term breast-feeding can increase the likelihood of cavities in young children. A study published in Pediatrics in June found there was a 2.4 times higher risk of severe cavities for children who were breast-fed for two or more years compared to those breast-fed for up to one year, according to a press release for the study. Breast-feeding “between 13 and 23 months had no effect on” cavities, the study said.

“There are some reasons to explain such an association,” the study's lead author, Dr. Karen Peres, told CNN. “First, children who are exposed to breast-feeding beyond 24 months are usually those breast-fed on demand and at night. Second, higher frequency of breast-feeding and nocturnal breast-feeding on demand makes it very difficult to clean teeth in this specific period.”